Phengaris alcon
| Alcon blue | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Lycaenidae |
| Genus: | Phengaris |
| Species: | P. alcon |
| Binomial name | |
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Phengaris alcon |
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| Synonyms | |
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Glaucopsyche alcon |
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Glaucopsyche alcon
Maculinea alcon (Denis & Schiffermüller, 1775)
Phengaris alcon, the Alcon blue or Alcon large blue, is a butterfly of the Lycaenidae family and is found in Europe and northern Asia.
There are five subspecies:
There has been controversy over whether Phengaris rebeli, currently regarded as an ecotype within the Alcons, should be listed as a separate species. The two types are morphologically indistinguishable and molecular analysis has revealed little genetic difference, mostly attributable to localized habitat adaptation. Still some maintain that they should be treated as distinct species, especially for conservation purposes, because they parasitise different host ant colonies and parasitise these ants at different rates, and also rely on different host plant species (Gentiana pneumonanthe in the case of Phengaris alcon and Gentiana cruciata in the case of Phengaris rebeli).
The species can be seen flying in mid- to late summer. It lays its eggs onto the marsh gentian (Gentiana pneumonanthe); in the region of the Alps they are sometimes also found on the related willow gentian (Gentiana asclepiadea). The caterpillars eat no other plants.
Like some other species of Lycaenidae, the larval (caterpillar) stage of P. alcon depends on support by certain ants; it is therefore known as a myrmecophile.
Alcon larvae leave the food plant when they have grown sufficiently (4th instar) and wait on the ground below to be discovered by ants. The larvae emit surface chemicals (allomones) that closely match those of ant larvae, causing the ants to carry the Alcon larvae into their nests and place them in their brood chambers. Once adopted into a nest, Alcon larvae are fed the regurgitations of nurse ants (just as other ant brood), a process called trophallaxis. This parasitic method is known as the "cuckoo" strategy and is an alternative to the predatory strategy employed by most other members of the genus such as Phengaris arion. Though less common, the cuckoo strategy has been found to have several advantages over the predatory strategy. For one, it is more trophically efficient than preying directly on other ant grubs, and as a result, significantly more cuckoo-type larvae can be supported per nest than predatory larvae. Another advantage of cuckoo feeding is that individuals, having pursued a higher degree of social integration, have a higher chance of surviving when a nest is overcrowded or facing food shortage because ants preferentially feed the larvae; compared to the type of scramble competition that can devastate predatory larvae, this contest competition results in much lower mortality. Though the cuckoo strategy has its advantages, it also comes with important costs; with greater host ant specialization comes much more limited ecological niches.
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Wikipedia